A functional haplotype in the 3'untranslated region of TNFRSF1B is associated with tuberculosis in two African populations.

RATIONALE

Susceptibility to tuberculosis is not only determined by Mycobacterium tuberculosis infection, but also by the genetic component of the host. The pleiotropic cytokine tumor necrosis factor-alpha is essential to control tuberculosis infection, and various tumor necrosis factor family members and their respective receptors may contribute to tuberculosis risk.

OBJECTIVES

To investigate four functionally relevant polymorphisms in the tumor necrosis factor receptor 2-encoding gene, tumor necrosis factor receptor superfamily member 1B, for association with tuberculosis susceptibility.

METHODS

Genotyping of four polymorphisms was performed in independent populations from South Africa (429 cases and 482 control subjects) and Ghana (640 cases and 1,158 control subjects), and the association of the variants with tuberculosis was tested using two case-control association studies.

MEASUREMENTS AND MAIN RESULTS

Single-point and haplotype analysis in South Africans revealed an association in the 3'untranslated region of the investigated gene. The T allele of rs3397 alone and/or the 3' untranslated region haplotype GTT may confer protection against tuberculosis insofar as both allele and haplotype frequencies were significantly lower in case subjects than in controls. The GTT genotype had previously been shown to increase the decay of tumor necrosis factor receptor 2 messenger ribonucleic acid, and messenger ribonucleic acid destabilization may represent a key molecular mechanism for disease susceptibility. Interestingly, the association signal appeared to be restricted to women. The genetic finding was validated in female participants from Ghana. The combined P value in the haplotype analysis was P = 0.00011.

CONCLUSIONS

Our finding emphasizes the importance of tumor necrosis factor/tumor necrosis factor receptor-mediated immune responses in the pathogenesis of tuberculosis.